Conveyor device and film formation apparatus for a flexible substrate

ABSTRACT

With a conventional cylindrical can method, a region used as a film formation ground electrode is a portion of the cylindrical can, and an apparatus becomes larger in size in proportion to the surface area of the electrode. A conveyor device and a film formation apparatus having the conveyor device are provided, which have a unit for continuously conveying a flexible substrate from one end to the other end, and which are characterized in that a plurality of cylindrical rollers are provided between the one end and the other end along an arc with a radius R, the cylindrical rollers being arranged such that their center axes run parallel to each other, and that a mechanism for conveying the flexible substrate while the substrate is in contact with each of the plurality of cylindrical rollers is provided.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a conveyor device and film formationapparatus for a flexible substrate.

2. Description of the Related Art

Processes capable of manufacturing at low cost in the mass production ofthin film solar batteries (solar cells) have been anticipated in recentyears. A method for continuous processing, in which unit operations,such as film deposition, printing, and laser processing, are performedin-line while unwinding a rolled-up flexible substrate and winding it uponto another roll is known as one of measures for reducing productioncost. This method is called a roll-to-roll method (hereafter referred toas roll-to-roll).

In particular, performing continuous conveying and continuous filmformation using a film formation apparatus that is provided with aroll-to-roll type conveyor device such as that shown in, for example,Japanese Patent Laid-open No. Sho 58-216475 or Japanese Patent Laid-openNo. Sho 59-34668, is effective as a means for increasing productivity ofa thin film formation process.

Continuous film formation is performed while continuously conveying aflexible film substrate in a film formation apparatus having aroll-to-roll type conveyor device. In order to efficiently form a filmto an objective thickness, one method is to lengthen a film formationelectric discharge electrode and increase the conveyor speed.

However, when using a generally small size, low cost parallel platemethod film formation apparatus for depositing a film to a flexiblesubstrate while conveying the substrate by a conveyor device, wrinklesin the substrate become a cause of irregular film formation, which is aproblem. A film formation apparatus in accordance with a parallel platemethod is shown in FIGS. 1A and 1B. FIG. 1A is a side face of the entirefilm formation apparatus, and FIG. 1B is the vicinity, of an electrode108 and a flexible substrate 101 as seen from below. The electrode 108is grounded, and a heater is incorporated therein to heat the flexiblesubstrate 101 as needed. Regarding a method of setting the substrate,first the flexible substrate is rolled out from a roll-out roll 105, theflexible substrate passes through gaps 103 formed in substrate conveyingportion side faces of a roll-out vacuum chamber 110 and a filmdeposition vacuum chamber 102, the flexible substrate passes between theelectrode 108 and an opposing electrode 109, passes through gaps 112 onthe right side of the film formation vacuum chamber, and then, is rolledonto a roll-up roll 104. In order to maintain the substrate in parallelwith the electrodes, a constant rotational torque is generated in theroll-up roll 104 and the roll-out roll 105, and a tensile force isapplied to the substrate. The substrate is in a state of being suspendedbetween guide rollers 106 and 107 at this time. Further, the flexiblesubstrate stretches and shrinks, and therefore a lengthening forceexists in the direction in which the substrate is being conveyed, and acontracting force exists in the width direction, in every portion of theflexible substrate suspended in the air and under application of thetensile force. This causes wrinkle 111 in the substrate. The expansionand shrinkage of the flexible substrate become large when heated by theheater, and wrinkle appears conspicuously. Furthermore, the film isformed with the portion that has been wrinkled exposed to an electricdischarge, and this is therefore a cause of uneven film formation. Thelonger the electrode, namely the longer the portion of the substratesuspended in the air, the higher the frequency of wrinkle becomes.

One method for stopping the flexible substrate from wrinkling is acylindrical can method. A film formation apparatus provided with aconveyor device in accordance with the cylindrical can method is shown,for example, in Japanese Patent Laid-open No. Sho 58-216475. By applyinga tensile force to a flexible substrate, and bringing the substrate intoclose contact with a curved surface of a cylindrical can, which supportsconveyance of the substrate, the wrinkles in the substrate can besuppressed. With a conventional cylindrical can method, a region used asa film formation grounding electrode is a portion of the cylindricalcan, and the apparatus becomes larger in size in proportion to thesurface area of the electrode. This increase in size is noticeableparticularly in a multi-chamber type film formation apparatus in which aplurality of vacuum chambers are connected in a row in order to performcontinuous film formation of PIN layers for forming a solar battery.

The increase in size cannot be avoided in a film deposition apparatusprovided with a conveyor device of cylindrical can method, but inthinking about making the apparatus smaller, a method of using animproved parallel plate method can be considered. In this improvedmethod, the portion contacting the flexible substrate and supporting theconveyance of the substrate may be made into a curved shape. A conveyordevice using a curved surface electrode as a conveyance supportingportion, and a film formation apparatus provided with the conveyordevice are shown in FIGS. 2A and 2B, respectively. A curved surfaceelectrode 201 serves as both a conveyance supporting portion and anelectric discharge grounding electrode. By applying a tensile force to aflexible substrate 204, the substrate is brought into close contact withthe curved surface electrode, and wrinkles in the substrate can besuppressed. This method is remarkably superior to the cylindrical canmethod with respect to the point of making the apparatus smaller, andmakes the apparatus a similar size comparable to that of the parallelplate method. However, a problem is that if the substrate is conveyedwhile a tensile force is applied thereto, the substrate, being incontact with the curved surface electrode during the conveyance,receives in its back surface abrasions due to rubbing between the backsurface of the flexible substrate and the curved surface electrode.Another problem is that the longer the electrode becomes, the larger thefriction force grows, which increases a force for winding up thesubstrate during conveyance and also increases a force working on thesubstrate to a considerable degree.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above, and an objectof the present invention is therefore to provide a film formationapparatus having a conveyor device of about the same size as aconventional parallel plate method conveyor device, which is moresuccessful in reducing size than a film formation apparatus having aconventional cylindrical can method conveyor device, and which cancontinuously convey a flexible substrate while preventing, wrinkles inthe flexible substrate and while preventing damage to the back surfaceof the flexible substrate.

The present invention is a conveyor device and a film forming apparatuswith the conveyor device which comprise means for continuously conveyinga flexible substrate from one end to the other end, characterized inthat:

a plurality of cylindrical rollers are provided between the one end andthe other end along an arc with a radius R, the cylindrical rollersbeing arranged such that their center axes run parallel to each other;and

a mechanism for conveying the flexible substrate while the substrate isin contact with each of the plurality of cylindrical rollers is used. Atensile force is applied to the flexible substrate and it is placed inclose contact with each of the plurality of cylindrical rollers.Wrinkles in the flexible substrate can thus be prevented, and it ispossible to continuously convey the flexible substrate while preventingdamage to the back surface of the substrate. FIG. 3 shows details.First, consider a curved surface 301 possessing an arc having a radius R(302) with a center axis 303 as the center. The curved surface 301 isshown for the explanation, and does not actually exist. Next, aplurality of cylindrical rollers 304 having an arbitrary length arelined up consecutively on the curved surface 301 so that gaps betweenthe rollers become as small as possible. Each center axis 305 of theplurality of cylindrical rollers 304 is on the curved surface 301, andis parallel with the center axis 303 of the curved surface 301. Inaddition, a tensile force is applied to a flexible substrate 306, sothat the substrate is brought into close contact with the plurality ofcylindrical rollers. Care that the plurality of cylindrical rollers 304are arranged such that a wrap angle at which the flexible substrate 306contacts each cylindrical roller 304 is always kept positive. Theconveyor device provided with means for continuously conveying theflexible substrate, and the film formation apparatus having the conveyordevice according to the present invention, are referred to as a curvedsurface roller method. In the conveyor device and the film formationapparatus therewith, it is proper that the radius R (302) is in a rangeof 0.5-10 m.

A method of arranging the cylindrical rollers is stated and shown inFIGS 4A to 4C. As shown in FIG. 4A, a curved surface 401 on which thecenter axes of the cylindrical rollers is arranged is taken as one type,and cylindrical rollers 402 may be lined up on the curved surface atequal gaps. When necessary, the gaps may not be equal but varied.Alternatively, as shown in FIG. 4B, the cylindrical rollers may be linedon a plurality of curved surfaces, the curved surface 401 and a curvedsurface 403, having different curvatures. Further, the diameter of thecylindrical rollers 402 may be different from one another. Considereddifferently, as shown in FIG. 4C, when a flexible substrate 407 isbrought into contact with each of the plurality of cylindrical rollers,provided that an arc angle of portions 404 at which the flexiblesubstrate contacts each of the cylindrical rollers, namely a wrap angle405, is positive, the wrap angle may be arbitrary. In order to stabilizea film formation state in the direction in which the substrate is beingconveyed, it is convenient to make all of the wrap angles uniform, butwhen there are mechanical restrictions such as the entire conveyordevice must be contained within a vacuum chamber, then the angles may befreely set. This means that a curvature 406 of the curved surface is notconstant but varies.

A film formation electric discharge electrode of a conventional parallelplate method is shown in FIG. 5A, and a film formation electricdischarge electrode that also serves as a conveyance supporting portionof the curved surface roller method conveyor device is shown in FIG. 5B.A state in which a tensile force is applied to a flexible substrate sothat the flexible substrate is brought into close contact with aplurality of cylindrical rollers is shown. With an electrode 504 of aconventional parallel plate method even if a tensile force 501 appliedto a flexible substrate 512 is large, only a component force 503 in adirection parallel to the electrode exists in a substrate surface 507opposing the electrode, and a component force 502 in a perpendiculardirection cannot be obtained. Only component force 509 and 510 exist inboth ends of the parallel plate method electrode. The component force505 also cannot be obtained for the case of the curved surface rollermethod provided that cylindrical rollers 511 are lined up on a straightline. However, provided that the flexible substrate 512 contacts each ofthe cylindrical rollers 511 with a wrap angle 508 which is positive, acomponent force 506 in a direction pressing the substrate against theelectrode is generated. Note that tensile forces and the componentforces are shown in FIG. 5B assuming that the flexible substrate and thecylindrical rollers are in point contact. Regarding the electrodes ofthe curved surface roller method, each cylindrical roller is in contactwith the substrate at a wrap angle of a positive value, and thereforeall of the cylindrical rollers can press against the flexible substrate.In other words, the flexible substrate can be placed in close contactwith the film formation electric discharge electrode that also serves asthe conveyance supporting portion or the conveyor device.

A film formation apparatus having a curved surface roller methodconveyor device is shown in FIGS. 6A and 6B. By shortening a portion ofa flexible substrate which is suspended in the air in the curved surfaceroller method by arranging the cylindrical rollers as close as possible,it becomes possible to obtain the same close contact effect for theflexible substrate as when on a continuous curved surface in thecylindrical can method, and wrinkles in the flexible substrate, alongwith film formation unevennesses at the time of film formation caused bywrinkles, can be prevented. Further, by rotating each cylindrical roller602 when the flexible substrate is conveyed, damage to the back surfaceof the substrate due to rubbing between the substrate and the filmformation electric discharge electrode can be suppressed.

Comparing a film formation apparatus having, a curved surface rollermethod conveyor device, and a film formation apparatus having acylindrical can method conveyor device, it is shown in FIGS. 7A and 7Bthat the apparatus for the curved surface roller method is moresuccessful in reducing its size. FIG. 7A is a film formation apparatushaving a curved surface roller method conveyor device and using anelectrode that also serves as a conveyance supporting portion, and FIG.7B is a film formation apparatus having a cylindrical can methodconveyor device and using a cylindrical can electrode 710 that alsoserves as a combination conveyance supporting portion. The conveyordevice of FIG. 7A is of a curved surface roller method with a radius ofcurvature R of 1000 mm, and the conveyor device of FIG. 7B is acylindrical can method with a radius R of 500 mm. The total electrodesurface area for each apparatus is about the same size. With thecylindrical can method, the radius can be kept at half of the radius ofcurvature in the curved surface roller method, but the entirecylindrical can must be set within the apparatus, and therefore theapparatus is inevitable large. In practice, not only is the sizedifference in the side face diagram important, but also the differencein volume of a vacuum chamber in a vacuum apparatus is very important.As the vacuum chamber is increased in size, a vacuum chamber wall usedhas to be thicker and more solid. Therefore the apparatus becomes veryheavy, and things such as building floor strength become problems. Thevacuum apparatus using a cylindrical can radius R of 500 mm may weightas heavy as 2 tons. Further, accompanying the increase in size of thevacuum chamber, components such as a vacuum pump used in an evacuationsystem also become large and high cost. There are many advantages inreducing the size of a film formation apparatus in which the electrodesurface area obtained is about the same size, particularly the vacuumapparatus.

A state of thermal conduction to a flexible substrate is shown in FIG. 8for a case of a plurality of cylindrical rollers in a curved surfaceroller method also used to heat the substrate. Regarding transfer ofheat from a heater block 803 with a heater body incorporated therein toa flexible substrate 807, there is heat transfer in a region 801 becauseof contacting a cylindrical roller 804, and there is heat transfer in aregion 802 from radiation by the heater block 803 and the cylindricalroller 804. When the substrate is conveyed the substrate passesalternately through the regions 801 and 802. In order to preventfluctuations in the substrate temperature, a gap 805 between the heaterblock and the roller, and a gap 806 between the heater block and thesubstrate, are preferably adjusted. Further, there may be differences inthe temperature of the substrate during high vacuum and during gasinjection, even with the same heater temperature setting, and adifference between a substrate temperature at a contact portion at theregion 801 and a substrate temperature at the radiated portion in theregion 802 also may vary depending on the conveyor speed, and thereforespecial attention is given at the time of measuring the substratetemperature and designing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B show flexible substrates in a conventional parallelplate method film formation apparatus;

FIGS. 2A and 2B show flexible substrates in a conventional curvedsurface electrode method film formation apparatus;

FIG. 3 shows an aspect of cylindrical rollers of a curved surface rollermethod of the present invention;

FIGS. 4A to 4C show arrangements of curved surface roller methodcylindrical rollers of the present invention;

FIGS. 5A and 5B dynamically illustrate tensile forces working onflexible substrates of a conventional parallel plate method and a curvedsurface roller method of the present invention, respectively;

FIGS. 6A and 6B show curved surface roller method film formationapparatuses of the present invention;

FIGS. 7A and 7B are diagrams for comparing the size of a curved surfaceroller method film formation apparatus of the present invention and acylindrical can method film formation apparatus;

FIG. 8 illustrates thermal conduction in the curved surface rollermethod of the present invention;

FIGS. 9A and 9B are graphs showing results of substrate temperaturemeasurements in a curved surface roller method film formation apparatusand a parallel plate method film formation apparatus, respectively; and

FIGS. 10A and 10B are graphs showing results of substrate widthdirection film thickness measurements in a parallel plate method filmformation apparatus and a curved surface roller method film formationapparatus, respectively.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[Embodiment]

An embodiment of the present invention is explained below. First, aconveyance supporting portion of a curved surface roller method conveyordevice is manufactured. The conveyance supporting portion is composed ofa curved surface block for transmitting heat from a heater uniformly,and a plurality of cylindrical rollers, which form a movable portion. Analuminum alloy having good thermal conductivity is used as a materialthereof. The size of the curved surface block is 428 mm by 300 mm, andthe maximum thickness is 30 mm. The radius of curvature R of the curvedsurface is set to 1000 mm. Next, 42 cylindrical rollers each having adiameter of 9 mm are attached through bearings across the curvedsurface. The angle between the cylindrical rollers is 0°35′. A gap 805between the cylindrical rollers 804 and a heater block 803 shown in FIG.8 is set to 1 mm. Further, a gap 806 between a flexible substrate 807and the heater block is set to 7 mm.

A film formation apparatus having a conveyor device like that shown inFIGS. 6A and 6B is prepared. This film formation apparatus is providedwith a conveyor device for a flexible substrate, a vacuum chamber, afilm formation gas introduction system, an evacuation system, and a highfrequency power supply introduction system which can generate an energysuch as an electromagnetic wave, and film formation is performed byplasma CVD. First, a conveyance supporting portion 610 of the curvedsurface roller method conveyor device is attached to a heater 609,forming the curved surface roller method conveyor device. The conveyancesupporting portion of the curved surface roller method conveyor deviceis used as a ground electrode. The high frequency power supplyintroduction system is composed of the curved surface roller methodground electrode and a high frequency power supply side electrode 608.Next, a flexible substrate 601 is set so as to be rolled out from aroll-out roll 607, to pass through a guide roll 606 and the curvedsurface roller method ground electrode 610, and to be rolled up by aroll-up roll 608. At this point, a constant rotational torque is appliedto the roll-out roll 607 in the opposite direction with respect to theroll-up roll 608, and therefore a tensile force is applied to theflexible substrate 601, which comes into close contact with the curvedsurface of the curved surface roller method ground electrode.

In order to measure temperature changes in the surface of the flexiblesubstrate 601, a thermocouple 611 is fixed in a certain position of thesurface of the flexible substrate, and the flexible substrate 601 isrolled up onto the roll-up roll 608 and conveyed. At this point theportion of the flexible substrate to which the thermocouple is fixedrecords the temperature changes every 1 second near a portion contactingthe curved surface roller method ground electrode 610. Measured valuesare shown in FIG. 9A. The measurement results are shown in differencefrom the average substrate temperature when the flexible substrate is incontact with the curved surface roller method ground electrode. Inconclusion, the substrate temperature is nearly constant when thesubstrate is in contact with the curved surface roller method electrode,and the degree of irregularity in the temperature is not so serious asto cause a problem. Strictly speaking, a temperature difference existsbetween the heat transfer portion 801 at which the flexible substrateand the cylindrical roller shown in FIG. 8 are in contact with eachother, and the heat transfer portion 802 where heat is radiated from thecylindrical roller and from the roller block, but this temperaturedifference is less than 1° C. For comparison, data at a time when aflexible substrate passes through a plate ground electrode portionhaving a built-in heater for a parallel plate method film formationapparatus having a conveyor device is shown in FIG. 9B. A 2 mm gap isformed between the flexible substrate and the plate ground electrodehaving the built-in heater, so that the substrate is not in contact withthe electrode and therefore heat transfer to the substrate when theflexible substrate passes through is always by radiation. Comparing withthis data, it can be seen that temperature unevennesses due to thecurved surface roller method electrode are suppressed and do not cause aproblem.

Wrinkles in the flexible substrate, and film formation unevennessescaused by the wrinkles, were evaluated. First, a PEN (polyethylenenaphthalate) film was used in a flexible substrate, and the substratewas set into the conveying system of the film formation apparatus havingthe conveyor device shown in FIGS. 6A and 6B. Then a tensile force wasapplied to the flexible substrate. The flexible substrate 601 wasobserved from a lower portion of the curved surface roller method groundelectrode, and no wrinkles were seen in the substrate. Next, silane gasand hydrogen gas were introduced into a film formation chamber 604, andan electric discharge was generated between the high frequency powersupply side electrode 608 and the curved surface roller method groundelectrode 610, performing film formation of non-single crystal siliconon the flexible substrate. Non-single crystal silicon denotes amorphoussilicon, microcrystalline silicon, and thin film polycrystallinesilicon. The film thickness of this film was measured using aspectrophotometer and scanning in the width direction of the substrate.Results are shown in FIGS. 10A and 10B. FIG. 10A shows a film thicknessdistribution in the substrate width direction of a film formed by usinga parallel plate method film formation apparatus, and FIG. 10B shows afilm thickness distribution of a film formed by using the curved surfaceroller method film formation apparatus. There were wrinkles in thesubstrate during film formation with the parallel plate method filmformation apparatus, and therefore the film thickness distribution wason the order of ±10% and color unevennesses could be observed even withthe naked eye. There were no wrinkles in the substrate during filmformation with the curved surface roller method film formationapparatus, the film thickness distribution could be suppressed toapproximately ±5%, and almost no color unevennesses could be verified byobserving with the naked eye. As a result, it can be said that filmthickness unevennesses can be suppressed.

As has been described, the present invention is a curved surface rollermethod conveyor device of about the same size as a conventional parallelplate method conveyor device, and a film formation apparatus having theconveyor device. The present invention thus can provide the conveyordevice and a film formation apparatus having the conveyor device whichare more successful in reducing size than a film formation apparatushaving a conventional cylindrical can method conveyor device, and whichcan continuously convey a flexible substrate while preventing wrinklesin the flexible substrate and while preventing damage to the backsurface of the flexible substrate.

1-7. (canceled)
 8. A multi-chamber type film formation apparatuscomprising: at least first and second vacuum chambers; a plurality ofcylindrical rollers in at least one of the first and second vacuumchambers, the cylindrical rollers being arranged along an arc whereincenter axes of the plurality of cylindrical rollers run parallel to eachother; at least a first roller and a second roller for continuouslyconveying a flexible substrate from the first roller to the secondroller; a flexible substrate passing along the first and second rollersand the plurality of cylindrical rollers such that the flexiblesubstrate is in contact with the plurality of cylindrical rollers with awrap angle kept positive; and an electrode opposed to the plurality ofcylindrical rollers with the flexible substrate disposed therebetween.9. The film formation apparatus according to claim 8, wherein theplurality of cylindrical rollers are provided with a heater.
 10. Thefilm formation apparatus according to claim 9, wherein a gap between theheater and the flexible substrate is adjustable.
 11. The film formationapparatus according to claim 8, wherein the plurality of cylindricalrollers are grounded and the electrode is connected to a high frequencypower supply.
 12. The film formation apparatus according to claim 8,wherein the apparatus is a plasma CVD apparatus.
 13. The film formationapparatus according to claim 8, wherein the film formation apparatus isused for forming a solar battery.
 14. The film formation apparatusaccording to claim 8, wherein the flexible substrate is a resin film.15. A multi-chamber type film formation apparatus comprising: at leastfirst and second vacuum chambers; at least one conveyance supportingportion in at least one of the first and second vacuum chambers andincluding a plurality of cylindrical rollers provided between a firstend and a second end along an arc with a radius R; at least a firstroller and a second roller for continuously conveying a flexiblesubstrate from the first roller to the second roller; and an opposingelectrode opposed to the conveyance supporting portion, wherein theflexible substrate is located between the conveyance supporting portionand the first and second rollers, wherein the flexible substrate islocated between the plurality of cylindrical rollers and the opposingelectrode, wherein center axes of the plurality of cylindrical rollersrun parallel to each other, wherein the substrate is in contact witheach of the plurality of cylindrical rollers with a wrap angle keptpositive to create a force in a direction pressing the flexiblesubstrate against the plurality of cylindrical rollers, with thesubstrate being curved so that the substrate has a concave surface incontact with the plurality of cylindrical rollers, and wherein theplurality of cylindrical rollers are provided with a heater.
 16. Thefilm formation apparatus according to claim 15, wherein the conveyancesupporting portion serving as a ground electrode.
 17. The film formationapparatus according to claim 15, wherein the radius R of the arc is in arange of 0.5 to 10 m.
 18. The film formation apparatus according toclaim 15, wherein the film formation apparatus is a plasma CVDapparatus.
 19. The film formation apparatus according to claim 15further comprising: an introducing means for introducing a gas into thevacuum chamber; a gas evacuation means; and an energy supplying meansfor supplying an energy to make a plasma from the gas.
 20. The filmformation apparatus according to claim 19, wherein the energy is anelectromagnetic wave.
 21. The film formation apparatus according toclaim 15, wherein the film formation apparatus is used for forming asolar battery.
 22. The film formation apparatus according to claim 15,wherein the flexible substrate is a resin film.
 23. A multichamber typefilm formation apparatus comprising: at least first and second vacuumchambers; at least one conveyance supporting portion in at least one ofthe first and second vacuum chambers and including a plurality ofcylindrical rollers provided between a first end and a second end alongan arc with a radius R; at least a first roller and a second roller forcontinuously conveying a flexible substrate from the first roller to thesecond roller; an opposing electrode opposed to the conveyancesupporting portion; and a heater for transferring heat to the pluralityof cylindrical rollers and the flexible substrate, wherein the flexiblesubstrate is located between the conveyance supporting portion and thefirst and second rollers, wherein the flexible substrate is locatedbetween the plurality of cylindrical rollers and the opposing electrode,wherein center axes of the plurality of cylindrical rollers run parallelto each other, wherein the substrate is in contact with each of theplurality of cylindrical rollers with a wrap angle kept positive tocreate a force in a direction pressing the flexible substrate againstthe plurality of cylindrical rollers, with the substrate being curved sothat the substrate has a concave surface in contact with the pluralityof cylindrical rollers, and wherein a gap between the heater and theflexible substrate is adjusted.
 24. The film formation apparatusaccording to claim 23, wherein the conveyance supporting portion servesas a ground electrode.
 25. The film formation apparatus according toclaim 23, wherein the radius R of the arc is in a range of 0.5 to 10 m.26. The film formation apparatus according to claim 23 furthercomprising: a vacuum chamber; an introducing means for introducing a gasinto the vacuum chamber; a gas evacuation means; and an energy supplyingmeans for supplying an energy to make a plasma from the gas.
 27. Thefilm formation apparatus according to claim 26, wherein the energy is anelectromagnetic wave.
 28. The film formation apparatus according toclaim 26, wherein the film formation apparatus is a plasma CVDapparatus.
 29. The film formation apparatus according to claim 26,wherein the film formation apparatus is used for forming a solarbattery.
 30. The film formation apparatus according to claim 26, whereinthe flexible substrate is a resin film.
 31. A method for manufacturingsemiconductor device comprising: providing a plurality of cylindricalrollers arranged along an arc in a chamber wherein center axes of theplurality of cylindrical rollers run parallel to each other; providingan electrode opposed to the plurality of cylindrical rollers in thechamber; moving a flexible substrate from a first roller to a secondroller wherein the flexible substrate passes through a space between theplurality of cylindrical rollers and the electrode; introducing a gasinto the chamber; applying an electrical energy to the electrode to forma plasma of the gas, and forming a film over the flexible substrate byusing the plasma, wherein the flexible substrate is curved so that theflexible substrate has a concave surface being in contact with theplurality of cylindrical rollers and a convex surface opposite to theconcave surface.
 32. The method according to claim 31, wherein a solarbattery includes the film.
 33. A method for manufacturing semiconductordevice comprising: providing a first conveyance supporting portionincluding a plurality of cylindrical rollers arranged along an arc in afirst chamber wherein center axes of the plurality of cylindricalrollers run parallel to each other; providing a first electrode opposedto the first conveyance supporting portion in the first chamber;providing a second conveyance supporting portion including a pluralityof cylindrical rollers arranged along an arc in a second chamber whereincenter axes of the plurality of cylindrical rollers run parallel to eachother; providing a second electrode opposed to the second conveyancesupporting portion in the second chamber; moving a flexible substratefrom the plurality of cylindrical rollers of the first conveyancesupporting portion to the plurality of cylindrical rollers of the secondconveyance supporting portion wherein the flexible substrate passesthrough a space between the first conveyance supporting portion and thefirst electrode and a space between the second conveyance supportingportion and the second electrode; introducing a gas into the firstchamber; applying an electrical energy to the first electrode to form aplasma of the gas, forming a first film over the flexible substrate byusing the plasma in the first chamber, introducing a gas into the secondchamber; applying an electrical energy to the second electrode to form aplasma of the gas, and forming a second film over the flexible substrateby using the plasma in the second chamber, wherein the flexiblesubstrate is curved so that the flexible substrate has a concave surfacebeing in contact with the plurality of cylindrical rollers and a convexsurface opposite to the concave surface in the first and secondchambers.
 34. The method according to claim 33, wherein a solar batteryincludes the first film and the second film.